{
语法百题 解题报告：
 http://git.oschina.net/et0662/sznoi-grammar/ 
}

function f(n:longint):longint;
begin
	if(n=0)then
		f:=1
	else
		f:=n*f(n-1);
end;
var
	a,b,c:integer;
begin
	readln(a,b,c);
	writeln(f(a)+f(b)+f(c));
end.
